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In this work, we report 3D printable soft composites that are simultaneously stretchable and tough. The matrix of the composite consists of polydimethylsiloxane containing octuple hydrogen bonding sites, resulting in a material significantly tougher than conventional polydimethylsiloxane. Short glass fibers are also added to the material. Prior to solvent evaporation, the material possesses a viscoelastic yield stress making it suitable for printing via direct ink writing. We mechanically characterize the printed composite, including fracture tests. We observe robust crack deflection and delay of catastrophic failure, leading to measured toughness values up to 2 00 000 J m −2 for specimens with 5 vol% glass fibers. The printed composites exhibit an unprecedented combination of stiffness, stretchability, and toughness.
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Quasi-Static Fracture Toughness and Damage Monitoring in Liquid Metal Reinforced Hybrid Composites
An experimental study is performed to investigate the quasi-static fracture toughness and damage monitoring capabilities of liquid metal (75.5% Gallium/24.5% Indium) reinforced intraply glass/carbon hybrid composites. Two different layups (G-0, where glass fibers are along the crack propagation direction; C-0, where carbon fibers are along the crack propagation direction) and two different weight percentages of liquid metal (1% and 2%) are considered in the fabrication of the composites. A novel four-probe technique is employed to determine the piezo-resistive damage response under mode-I fracture loading conditions. The effect of layups and liquid metal concentrations on fracture toughness and changes in piezo-resistance response is discussed. The C-composite without liquid metal demonstrated higher fracture toughness compared to that of the G-composite due to carbon fiber breakage. The addition of liquid metal decreases the fracture initiation toughness of both G- and C-composites. Scanning electron microscopy images show that liquid metal takes the form of large liquid metal pockets and small spherical droplets on the fracture surfaces. In both C- and G-composites, the peak resistance change of composites with 2% liquid metal is substantially lower than that of both no-liquid metal and 1% liquid metal composites.
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- Award ID(s):
- 2149893
- PAR ID:
- 10568440
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Journal of Composites Science
- Volume:
- 8
- Issue:
- 1
- ISSN:
- 2504-477X
- Page Range / eLocation ID:
- 25
- Subject(s) / Keyword(s):
- Liquid metal intraply hybrid composites quasi-static fracture toughness damage monitoring
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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